Some conditions have been referred to as Obsessive-compulsive (OC) spectrum disorders on the basis of clinical similarities to OCD (i.e., recurrent disturbing ideas and/or irresistible urges), higher than expected co-occurrence with OCD and favorable response to SRIs (the medications that tend to work in OCD). Two of the most frequently cited OC Spectrum Disorders are body dysmorphic disorder and trichotillomania.

Body Dysmorphic disorder (BDD)

The central feature of BDD is a preoccupation with an imagined or inconsequential defect in physical appearance. The clinical characteristics of BDD and OCD are similar in many respects. Both disorders are characterized by recurrent, disturbing and intrusive thoughts. In the case of OCD, the content may involve a variety of different subjects (e.g., contamination or fear of acting on unwanted impulses). The concerns of BDD, by definition, always involve a minor or imagined physical abnormality. The most frequent concerns relate to the face and head (e.g., nose size, facial shape, skin texture, wrinkles or blemishes); less frequently, other aspects of the body are the focus of attention (e.g., breast asymmetry and foot size). Repeated checking (e.g., examining the imagined defect in the mirror) or touching often accompanies BDD; such behaviors are very similar to those found in classic OCD. Instead of engaging in checking rituals, some patients with BDD may endeavor to avoid all reminders of their flawed appearance by removing mirrors and covering all reflective surfaces in their home.

In contrast to OCD, patients with BDD usually are convinced that their irrational preoccupations are justifiable. However, when presented with contradictory evidence (e.g., graphs showing that oneÆs measured head size is within normal limits), a BDD patient will acknowledge that there is no objective support for the concern. Thus, the overvalued ideas of BDD fall somewhere between obsessions and delusions with respect to how strongly false beliefs are held to be valid.

Several studies suggest that serotonin reuptake inhibitors (SRIs) are beneficial in BDD. In my own experience, BDD tends to be less responsive to medication treatment than OCD.

Trichotillomania

The key features of trichotillomania are 1) recurrent hair pulling, 2) mounting tension preceding the act, and 3) pleasure or relief accompanying the act. The sites most often affected are the scalp, eyebrows, eyelashes, extremities and pubic hair. Some patients eat their hair (trichotillophagia). The bald spots can be obvious and may require wigs or extensive makeup to camouflage. Rather than feeling gratification following hair-pulling, patients are more likely to experience regret over the disfigurement or frustration with their loss of self-control.

Although hair-pulling can occur during periods of heightened stress, patients seem most vulnerable during times of idleness, like while watching TV, reading or driving home from work. This observation has led to the suggestion that trichotillomania is better conceptualized as a habit disorder than as an impulse control disorder. The behavior therapy technique (habit reversal) that seems most beneficial for treating trichotillomania was originally developed for maladaptive habits. Some authors have proposed that pathological grooming is the common thread running between trichotillomania, onychophagia (compulsive nail biting) and some forms of OCD.

Despite similarities between trichotillomania and OCD, the differences between these conditions are equally noteworthy. While early reports of trichotillomania emphasized its co-occurrence with OCD and favorable response to SRIs, later studies indicate that trichotillomania often exists in isolation and that medication treatment often fails. In contrast to OCD, many more women than men are affected. The hypothesis that OCD and trichotillomania are mediated by shared brain pathways was called into question after brain-imaging studies revealed differences between the two disorders.